1. Field of the Invention
The invention is related to the field of communications, and in particular, to bandwidth selection in a communication network.
2. Description of the Prior Art
Many institutions, such as businesses and corporations, have computer systems that are used for many purposes, such as bookkeeping, records, inventory, communications, document processing, employee and customer records, technical or informational databases, etc. It is no exaggeration to say that a computer system has become an indispensable part of most institutions.
Obtaining and maintaining information is very important to most institutions. Therefore, preventing the loss of computerized information is very critical. Consequently, most institutions have some manner of disaster recovery plan, wherein data is mirrored (i.e., copied and stored) at a physically remote location. The mirroring typically is performed on a periodic basis, but can also be done at the initiation of a system operator or upon creation and/or modification of data. In the event of data loss, whether complete or partial, the mirrored data can be used to reclaim files and maintain operation of the institutional computer system.
FIG. 1 is a diagram of a mirroring system according to the prior art. In the prior art, the institution accesses and uses a mirror site that includes a mass data storage capability. A common mirror site is a Storage Area Network (SAN) that includes mass storage devices and a controller that are available over a communication network. Multiple institutions can access the SAN over the communication network and store and retrieve data.
The communication network can comprise any manner of network. In one example, the communication network is a packet network, such as the Internet, for example. However, a packet network is of a low bandwidth and relatively slow, can experience varying levels of traffic congestion, and can be an impediment to efficient storage operation when a large amount of data is to be mirrored. Another prior art approach has been to use a switched network that employs a dedicated, point-to-point connection for data transfer. One example of such a network is an optical fiber, switched telephone system.
However, the drawback in the prior art approach to mirroring has been that SANs are unforgiving of delay. Delay in a mass data transmission, such as transmission delay due to a relatively low bandwidth level, can increase the data latency. The data latency can result in storage of individual portions of data that lags in time from actual changes in the original data. Consequently, when high data latency is present, a failure at the institutional computer system can result in some data being irretrievably lost, i.e., data that was in transmission and that was not yet backed up at the destination. As a result, large institutions seek to use the highest available bandwidth that can be cost justified. However, in the prior art, this has led to a situation where a trade-off decision had to be made between reliability and cost. In addition, a communication link bandwidth that is acceptable at one point in time can be too slow during a subsequent mirroring session.
The prior art approach is generally to use a pre-assigned bandwidth for all mass data transfers. This prior art approach does not give a system operator choices as to what bandwidth can be used in order to avoid traffic congestion problems and successfully accomplish a mirroring operation. If the prior art allows a bandwidth selection or configuration, the system operator must perform pre-selection when access is purchased or must be able to generate and format relatively complicated system commands, and cannot easily and quickly select an appropriate bandwidth for a mirroring session.